This invention relates to folding and loading of thin, limp, sheet-type articles into a receptacle therefor and particularly relates to folding and loading of small plastic bags, such as sandwich bags, into a dispensing box or carton. It also, more particularly, relates to an improved transporting mechanism for transporting a sheet-type article from a conveyor to a folding station and to the combination of the transporting mechanism with the conveyor and folding station.
Plastic sheet materials present many handling and dispensing problems which are magnified when the sheet is thin, limp, and subject to loading by static electricity. Exemplary plastic sheet materials which are used in large quantities at the present time are plastic bags, such as trash bags, product bags and sandwich bags. Many of these bag products are assembled, shipped and dispensed in roll form. Others, however, are preferably handled in folded form because of consumer preferences, economy in storage, and/or ease of handling and dispensing. Folding of such bags can be performed by in-line machinery without great difficulty when the bags are large, as, for example, bulk bags and trash bags.
However, when the bags are quite small, such as sandwich bags, for example, so many difficulties occur with presently available machinery that the present practice is to use manual labor for folding and loading plastic sandwich bags into dispensing boxes therefor. There is consequently a need for new concepts and arrangements that will overcome the specific problems peculiar to folding and loading of such thin plastic articles of relatively small size. These difficulties arise because the bags must be sequentially picked up from a conveyor, folded, folded again, transported to a receptacle, loaded into the receptacle and pressed against its bottom in order to remove entrapped air. In each of these operations, the lightness, limpness, thinness and smallness of the bags present special handling problems, particularly when static electricity is present. Simply scaling down conventional folding machines does not solve these problems because the prior art devices inherently rely upon significantly greater stiffness, bulk, basis weight and like properties.
A method for sequentially packaging flexible plastic refuse bags is taught in U.S. Pat. No. 3,842,568, which comprises reeling a bag into a mandrel, pulling it sidewise in reeled condition from the mandrel and tamping the reeled bag into a carton.
An apparatus is described in U.S. Pat. No. 3,918,699 for multiple folding of soft articles, such as textile and paper articles. It includes a plurality of cooperating longitudinal and transverse folding arms which are operable according to a predetermined sequence and which cooperate with folding plates. More specifically, the middle portion of an article to be folded is brought under a folding plate, while its side portions lie on the longitudinal side folding arms of the machine. The side folding arms then operate toward each other in sequence so they form two folds and longitudinally overlap the two side portions. This prefolded article is next delivered to a second folding station where transversely disposed folding arms sequentially perform similar single foldings. The longitudinally and transversely folded article is finally delivered to a stacking station.
An apparatus and method for folding textile materials is taught in U.S. Pat. No. 4,008,887. It comprises a plurality of pivotal folding flap plates for sequentially folding the material, while gripping devices at the movable plates prevent unfolding and/or shifting of the material. The gripping members are C-shaped fingerlike elastic elements mounted on rotatable gripper shafts which are connected to rotatable flexible shafts and to a control mechanism for sequentially controlling the rotation of the shafts.